just brothers not "an brothers" lol
http://www.mangago.me/read-manga/brothers_yamamoto_kotetsuko/
The sequel (still unfinished):
http://www.mangago.me/read-manga/brothers_plus/
Who cares?
BrotherxBrother http://www.mangago.me/read-manga/brother_x_brother/
Some yaoi between an brothers, preferably adopted. Thanks!